code: def test_positional_arg_error(self):
      class SomeLayer(layers.Layer):
          def call(self, x, bool_arg):
              if bool_arg:
                  return x
              return x + 1
  
      x = backend.KerasTensor(shape=(2, 3), name="x")
      with self.assertRaisesRegex(
          ValueError, "Only input tensors may be passed as"
      ):
          SomeLayer()(x, True)
  
      # This works
      SomeLayer()(x, bool_arg=True)
  
imports: import numpy
  import pytest
  from keras import backend
  from keras import layers
  from keras import metrics
  from keras import models
  from keras import ops
  from keras import testing
label_desc: Use image node_id 2 for calling the LayerTest obj's underlying member method code with example usage: obj.test_positional_arg_error() and returns: unknown, x